In-line fluid pump



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Patented May 24, 1949 SEARCH ROOM UNITED STATES PATENT OFFICE IN-LINE FLUID PUMP Robert E. Snyder, Los Angeles, Calif.

Application December 20, 1943, Serial No. 514,927

18 Claims. 1

This invention relates to in-line fluid pumps and more particularly to a pump in which opposed helical blades are driven in opposite directions.

In the past pumps of this type have been constructed with two sets of helical blades separated from each other with an outlet port between them, so that when they were driven by a common source the fluid was picked up by the rotating blades and pumped toward a common center, thus building up pressure and forcing the fluid through the outlet port.

The object of the present invention is to pump fluid in one direction through an in-line pair of helical blades that are positioned in an opposed pitch relationship and are driven in opposite directions.

A further object of the present invention is to provide means of pumping fluid through an inline pump in two or more stages having opposed relationship to reduce the fluid whirl imparted by the pump blades.

A still further object of the present invention is to provide an in-line pump having a balanced load on the helical blades as well as having a balanced load on the driving members.

A further object is to provide an in-line pump which is instantly reversible.

A still further object is to provide a pump which permits the uniterrupted flow of fluid therethrough when not in operation.

A further object is to provide a pump in which each stage of operation has a pair of opposed helical blade conveyors that are rotated in opposite directions at the same R. P. M., and in which the stages are operated at different R. P. M.

A further object is to provide means of pumping fluid through an in-line pump, said means comprising two sets of helical blades in opposed relation driven in opposite directions and provided with means to chop oh. the fluid at a low fluid velocity at the entrance to the pump, to chop off the fluid at a high velocity at the point of changing the direction of whirl imparted to the fluid and dropping the fluid velocity at the exit port of the pump.

A further object is to provide a pair of helical blades in opposed relationship in an in-line pump in which the lead of the blade as it approaches the chop-off point is decreased to provide an increased forcing or ramming of the fluid to effect an increase in the fluid velocity flow across the chop-off point.

A still further object is to provide an in-line pump having a pair of helical blades in opposed relationship, in which means is provided to rotate the blades in opposite direction, and means is also provided to scoop with the outer blade of one rotor the fluid passing from the inner blade of the other rotor.

A still further object is to provide an in-line pump having a pair of helical blades in opposed relationship, in which means is provided to rotate the blades in opposite direction, and means is provided to restrict the chop-01f area to assist in forcing or ramming the fluid therethrough, and further means is provided to difiuse the fluid centrifugally by the outer blades of the opposed rotor to assist in creating a lower velocity passing from the exit port of the pump.

A further object is to provide a plurality of stages of opposed helical blade pumps driven from a common source, with means to step up the fluid pressure while maintaining a balanced load on the driving members.

A further object is to provide a plurality of stages of opposed helical blade pumps in which each stage is driven in an opposite direction to provide a plurality of chop-oil? positions and thus a plurality of fluid pressure step-ups.

A further object is to provide a plurality of balanced stages of helical blade pumps in opposed relationship driven in opposite directions which pump a fluid to a common center or discharge port.

A further object is to provide two stages of hellcal blade pumps in opposed relationship that are driven in opposite directions which permit a step-up in fluid pressure while changing the direction of fluid flow.

A further object is to provide a plurality of stages of helical blade pumps in opposed relationship that are driven in opposite directions in which one or more deliver the fluid to a common center and means to pump the fluid to one or more ports with a plurality of stages of the same unit,

A further object is to provide a plurality of stages of helical blade pumps in opposed relationship that are driven in opposite directions in which one or more deliver the fluid to a common center and means to pump the fluid from that common center.

A further object is to provide a plurality of units of helical blade pumps in opposed relationship that are driven in opposite directions and are arranged in parallel relationship in a common casing with intercommunicating passages from one unit to the next.

A further object is to provide a plurality of connected stages of helical blade conveyors in which each subsequent conveyor is in opposed relationship and is driven in an opposite direction and in which the conveyors are arranged in parallel relationship in a common casing with intercommunicating passages from one conveyor stage to the next and in which all conveyors are driven from a common source.

A further object is to provide a plurality of units in which two sources of drive are provided with a slip clutch to permit the use of either.

A further object is to provide one means to rotate the units enough to provide a minimum pumping action to assist the normal flow of fluid therethrough and another means to provide a maximum pumping action to cause the maximum capacity of flow therethrough.

Other objects and characteristics may become apparent from the accompanying drawings and detailed description of this invention; in which Fig. 1 is a perspective view of one embodiment.

Fig. 2 is a cross-sectional view taken on the line 2-2 of Fig. 1;

Fig. 3 is a schematic illustration of a method of driving a plurality of units shown in Figs. 1 and 2;

Fig. 4 is a cross-sectional view similar to Fig. 2, but provided with a fluid guide member, between the opposed blades.

Fig. 5 is a perspective view of the fluid guide member;

Fig. 6 is a schematic illustration of another embodiment of a driving means for the units as illustrated in Fig. 4; having fluid guides between each of the opposed blade members.

Fig. '7 is a view, partly in section, illustrating the helical blade aflixed to the tube;

Fig. 8 is a cross-sectional view of another embodiment of the invention;

Fig. 9 is a cross-sectional view of a further embodiment of the invention;

Fig. 10 is a cross-sectional view of a still further embodiment of the invention;

Fig. 11 is a cross-sectional view of another embodiment of the invention;

Fig. 12 is a schematic illustration of the method of drive in another embodiment of the invention;

Fig. 13 is a further schematic view of the means of driving in a still further embodiment of the invention;

Fig. 14 is a schematic illustration of another manner of driving the units in a further embodiment of the invention;

Fig. 15 illustrates schematically another embodiment of the invention;

Fig. 16 illustrates schematically another embodiment of the invention similar to Fig. 15;

Fig. 1'7 is a schematic illustration of a further development of the embodiment illustrated in Fig. 15;

Fig. 18 is a cross-sectional view of another embodiment of the invention;

Fig. 19 is a schematic illustration of a method of driving a plurality of units and Fig. 20 is a schematic illustration of a method of driving the units with two motors, using override clutches.

Fig. 21 is a sectional view of one type of override clutch taken along line 2|2l of Fig. 20.

With the above and other objects in view, one embodiment of the invention as illustrated in Fig 1 comprises a housing member composed of two halves 3| and 32 which are bolted together as illustrated in Figs. 1 and 2. A driving motor 33 is also bolted to the housing 3|, 32. Within the housing members 3|, 32 there are mounted tubular sleeves 34 and 35 having a common shaft 36 on which they are freely rotatable The shaft 36 is mounted at either end in a fluid guide member 31 which may be a part of the housing or may be mounted as a separate member at either end opening of the housing. Welded to and made an integral part of the sleeves 34 and 35 are pinion gears 4| and 42 so spaced as to mesh with a common drive gear 43 mounted on the drive shaft 44 of the driving unit 33. Also mounted within the sleeve 34 and 35 and made an integral part therewith are helical blades 39 and 40, shown in Fig. 2 and formed in opposite pitch relationship. The tubular sleeves 34 and 35 with their helical blades 39 and 40 respectively form a pair of fluid conveyors. The unit in Fig. 2 is shown bolted to a pipe line 50 at either end, and is also provided with adequate bearings to take care of any end thrust. The normal method of packing shall be provided to prevent fluid leak age, and special means of packing may be provided for certain fluids.

In operation, the unit 33 will drive pinion 43 through its shaft 44. The pinion 43 is in mesh with the pinions 4| and 42, driving them in opposite directions. The pinions 4| and 42 being mounted on and affixed to the tubes 34 and 35 will cause them to rotate in opposite directions. driving the helical blades 39 and 40 in opposite directions. A fluid supply in the line 50 will be picked up by the helical blades of the fluid conveyors. Assuming that the direction of rotation is from the side indicated by the arrow, the fluid will pass into the blade 39 and be forced to the central point of the unit where the opposed blade 40 rotating in an opposite direction will chop oil the fluid and will continue to force the fluid through as indicated by the arrow into the line 50, but the tendency to whirl has been reversed by the change of direction of rotation. In the event the driving unit 33 were reversed in the direction of rotation, the whole unit would be reversed and the fluid would flow in the opposite direction to that indicated by the arrows. Referring to Fig. 3, the schematic illustration of two stages A and B of the above unit with its drive is indicated in which the drive 33 by means of a gear 5| drives two gears 52 and 53 in the same direction of rotation. This, in turn, drives the common gear 43 and 43' of the units A and B which, in turn, drives the units as described above. In this embodiment there will be three high-speed cut-offs l5, l6 and IT in which the fluid is chopped off" by the oppositely rotating helical blades. Likewise, there will be two low speed cut-offs at each of the ends l8 and I9.

Referring to Fig. 4 which is similar to Fig. 2, all the parts are similar except that a fluid guide 58 is mounted in the center of the unit. This fluid guide member supports the central shaft 36 at its center and separates the chop ofl action of the blades by the tidth of the guide member.

Referring to Fig. 5, the fluid guide member 58 is shown in perspective with two flanges 53 and 60 to permit the tubes to fit snugly thereto to seal the fluid passing therethrough. Fig. 5 also shows the cut away portion 6| to permit the drive gear to be inserted as indicated in Fig. 4.

Fig. 6 illustrates a gear train similar to Fig. 3 but in addition having guide members 58 mounted at the points l5. l6 and I1. This, in effect. changes the high speed cut-ofl of Fig. 3 at points l5, l6 and I! to low speed cut-ofl points at either SEARCH ROOM side of the guide member. This form is specially useful in handling certain types of fluids, determined by the physical characteristics and composition of the fluid.

Fig. 7 illustrates a unit similar to 34, 35 of Figs. 2 or 4, in which the helical blade is amxed to a tube and also to a central member 62.

It should be noted that there is a certain critical speed at which the helical blades will bite most efliciently into a given fluid such as gas or liquid. The so-called chop-01f point is that point where the helical blade cuts off the fluid from the normal stream entering the rotating member. Where a single screw or helical blade is used in a fluid, the maximum chop-off between the blade and the fluid is governed by the R. P. M. between the moving blade and the fluid remaining at a stationary position or flowing in a straight line position. Thus, it is apparent that high chop off is attained only by high R. P. M.

In the present invention where opposing helical blades are used the fluid passing through this train from one end to the other, the maximum high speed chop off between the fluid and the blade will be governed by the sum of the individual blade R. P. M.s or the R. P. M. difference between them. For example, in the present invention, referring to Fig. 2, we may assume that the drive pinion is operating at 1800 R. P. M. If both pinions meshing with this main pinion are of the same size they will also be operating at 1800 R. P. M. Therefore, the chop off speed of the blades between the tube and the stationary pipe 50 connected therewith will be 1800 R. P. M. but the chop oil speed between the two tubes 34 and 35 will be 3600 R. P. M. Thus, in this example we have two low-speed chop offs of the fluid and one high-speed chop off. In this instance the fluid being pumped might be water. In other instances the R. P. M. might be considerably lower if the fluid were of high viscosity.

In Fig. 3 there is illustrated two low speed chop off and three high speed chop of]? positions.

In Fig. 4 we have three low speed chop off positions. In Fig. 6 we have five low speed chop oif positions and so we may form various combinations according to the desired characteristics of the fluid that is intended to be pumped.

Referring to Fig. 8, there is illustrated another embodiment of the invention in which the two opposed helical blade members 34 and 35 are formed with a central member 10 in which there is a decreasing bore caused by increasing the diameter of the central element so that we have a low velocity chop off position at its outer end and a very high velocity fluid point at the inner end. thus causing a high velocity chop off position where the opposing helical blades pass each other.

Fig. 9 illustrates a still further embodiment of the invention in which a similar effect is obtained to that already illustrated in Fig. 8 in which the tubes 34 and 35 have mounted therein helical blades in which the pitch of the blade is changed the center but its inner blade cut back considerably from the center; whereas unit 35 has its inner blade extended far past the center and its outer blade cut back from the center of the pair. Thus, in operation, the unit 35 will tend to push or ram the fluid forward to a position where the outer blade of unit 34 will pick up the fluid and throw it outward in a centrifugal action, ramming it on through the tube 34.

Referring to Fig. 11, a still further embodiment of the invention is illustrated in which the central portion 12 or chop off point between the two units is restricted. Thus, in operation, the unit 35 will tend to ram a fluid through the restricted area 12 and the unit 34 will pick up the fluid and throw it out in a centrifugal action, forcing it onward through this unit. This tends to create a lower pressure at the outside of unit 34.

Fig. 12 illustrates a spider or idler gear drive which may be mounted in a housing (not shown) and in which the unit 34 and unit 35 have two pinion gears 4|, 42 mounted thereon and afflxed thereto. Through the outer gears 4| and 42 and an auxiliary spider gear 13 and 14, similar units 34a and 35a are driven at the same R. P. M. This will, in effect, give a combination wherein there is a constant velocity flow through the unit and in which are two low speed fluid cut off points l8 and I8 and three high speed fluid cut off points |5, I6 and I1 thereby forming a train of units, each driving the next adjacent through a spider gear mounted in a stationary housing (not shown).

Fig. 13 illustrates another embodiment in which the shaft 36a is keyed to drive tubes a and c, and in which tubes 27 and d ride freely on the shaft. Therefore, through spider gears held by a stationary housing (not shown) tubes b and d will be driven in a reverse direction from tubes a and 0. Thus, in this combination we obtain three high speed fluid chop off points and two low speed fluid chop off points, and in which the drive is by shaft 36A in line with the tubes a, b, c, and d.

Referring to Fig. 14 there is illustrated a mixer type in which the central spindle 36B, drives the units either side thereof and is similar to Fig. 12, the unit 34 will drive unit 34a and the unit 35 will drive unit 35a but in this embodiment the fluid is pumped from either end towards or away from a common center depending upon the direction of pitch of the helical blades in the tubes.

In Fig. 15 we have another embodiment wherein a drive shaft 36B meshes by means of a pinion 43 with a pinion 4| which, in turn, meshes with a pinion 42. This arrangement permits a unit to pump fluid from the outer end to the center wherein the other unit picks it up and pumps it to the outer end of the unit and permits a right angle turn in the fluid flow.

Fig. 16 illustrates a similar arrangement wherein the drive shaft 360 is connected directly to the pinion 4|.

Fig. 17 illustrates a further embodiment wherein the drive shaft 363 through pinion 43 meshes with a pinion 4| and a pinion 40 and they in turn mesh with a pinion 42. In this arrangement the unit driven by pinion 42 will pump fluid from its outer end to a common center where the unit driven by pinion 40 and the unit driven by pinion 4| will pick up fluid and pump outwardly. Other fluid direction obviously may be obtained by changing the direction of the helical blades.

Fig. 18 illustrates an embodiment wherein two pumping units such as 34 and 35 of Fig. 2 have been mounted in parallel relationship in a casing so that a drive gear 36D by means of a gear 43a will drive the gear 4la which in turn drives the gear 42a. Thus, the direction of rotation of 34 and 35 will be opposite. The fluid pumped through 34 will pass into a communicating passageway which leads to the end of unit 35, unit 35 in turn pumping the fluid to its opposite end. This type is useful as a fluid agitator or mixer located on the outside of a mixing vat or tank.

Fig. 19 illustrates a schematic arrangement somewhat similar to Fig. 18 in which the drive shaft 36E and gear 43a are mounted centrally and the units 34, 34a, 35 and 35a are mounted in parallel relationship around the drive. Thus, when these units are contained within a housing (not shown) similar to Fig. 18 the fluid will be carried in a path as indicated by the arrows. We will thus have a continuous path for the fluid through four stages of pumping operation and in which there will be a low velocity chop ofi position at either end of each pumping unit.

Another embodiment of this invention is illustrated in Figs. 20 and 21 and is comprised of a housing member composed of two halves 3| and 32 which are fitted together substantially as illustrated in Fig. 1. Two driving motors 33a and 33b are also bolted to the housing 3|, 32. Within the housing member 3|, 32 there are mounted tubular sleeves 34, 35 having a common shaft 36 on which they are freely rotatable. The shaft 36 is mounted at either end in a fluid guide member 31 which may be a part of the housing or may be mounted as a separate member at either end of the housing opening. Welded to and made an integral part of the sleeve 34, 35 are pinion gears 4|, 42, so spaced as to mesh with a pair of common drive gears 43a and 43b, mounted on the stub drive shaft ll of the driving motors 33a and 33b thereof. The stub drive shaft l I of each unit is an integral part of the free wheeling clutch ll] illustrated in Fig. 21. The shaft H is keyed to a rotor I2, mounted within the gears 43a and 43b and due to the roller balls l3 acting on the cam faces l4 free wheeling or rotation of the shaft II in a counter-clockwise direction causes rotation of the gear member 43a or 431) but rotation in a clock-wise direction permits free wheeling or the rotation of the outer gear member 43a, 43b in a counter-clockwise direction while the shaft II is stationary will permit free wheeling or free rotation.

Also mounted within the sleeve 34 and 35 and made an integral part therewith are helical blades 39 and 40 shown in Fig. 20 and formed in opposite pitch relationship. The unit in Fig. 20 is shown bolted to a pipe line at either end.

Thus, Fig. 20 illustrates a sectional view of an in-line pump having two motors 33a, 33b, the motor 33a being the idling motor which is used only to drive the pump when it is not under load; the motor 33b being the pumping motor which is only used when the pump is under load. As already described, the motors are both connected to the tubular members: however, the motors are not connected directly to each other, but rather are connected to the unit by means of two free wheeling clutches as already described. The over-ride clutches may be of any conventional form, one form having been described as an example herein. The motor 33a is operating, the over-ride clutch of motor 33b will slip and will not drag motor 33a with it; conversely, when 8 motor 33b is in operation, the over-ride clutch of motor 33a will not be driven. Thus, in automatic operation of this embodiment of the inline pump, if a flow of fluid through the line is enough so that it isnt necessary for the main pump 33b to operate, the pump 33a will rotate the pump unit fast enough so that there will be no back pressure or loss of pressure in the line resulting from resistance to the passage of fluid through this pump. The motors 33a and 33b may be controlled remotely and governed by the desired flow of fluid through the line 50. It is to be noted that when motor 33a is operating that its R. P. M. is just enough to overcome any fluid flow loss resulting from fluid passing through the pump; therefore, it should push just a small amount on the fluid so there is no danger of the line developing back pressure.

The foregoing description is not intended to limit the present invention which extends to all changes, modifications and equivalents within the scope of the appended claims.

What is claimed is:

1. An in-line fluid pump comprised of two helical blade conveyors contained within a common housing and mounted on a common shaft in juxtaposition, with their blades in opposite pitch relation, means to rotate said conveyors slowly with the nomuidffiow through said pump Without interference when the pump is not pumping, and a segondme ans tgrotate saidconveyors rapidly toiforc fluidthrougthf'said pump.

2:"Aniii liri'e fluid pump comprisedo'f'two helical screw blade conveyors contained within a common housing and rotatably mounted on a common shaft in juxtaposition, with their blades in opposite pitch relation, and gear means to drive said conveyors from either of two motors so that one of said motors provi e mi um pumping action while the other of said motors provides a maximum pumping action.

3. An in-line fluid pump comprised of two helical screw blade conveyors contained within a common housing and mounted on a shaft, with their blades in opposite pitch relation, and

means to drive said conveyors from either of two motors so that one of said motors provides a minimum pumping action while the other of said motors provides a maximum pumping action, each motor being mechanically disconnectable from said drive means when the other of said motors is operating.

4. In an in-line pump, a housing in which a plurality of helical blade conveyors are contained, said helical blade conveyors being comprised of a sleeve with the helical blades affixed thereto, a common mounting shaft, said helical blades being in opposite pitch relation, said helical blade conveyors being mounted in juxtaposition, each of said conveyors having a gear affixed to the periphery of its sleeve member, and two slip clutches being connected to each gear by a similan-gear, said slip clutches being in turn connected to a motor, and the two motors being of diflierent horsepower.

5. Inan in-line pump, a housing in which a plurality of helical blade conveyors are contained, said helical blade conveyors being comprised of a sleeve with the helical blades affixed thereto, a shaft, said helical blades being in opposite pitch relation, said helical mounted in juxtaposition, each of said conveyors having a gear amxed to the periphery of its sleeve member, and clutch means connected to said blade conveyors being SEARCH ROOM gears, said clutch means being in turn connected to two motors of different horsepower.

6. An in-line pump adapted to provide two output pressure ranges, which includes a pair of helical screw blade conveyors contained within a common housing, one of said conveyors being adapted to pass its fluid into the other of said conveyors, and gear means to drive said conveyors from either of two drives, one of said drives providing a horsepower input just sufficient to prevent back pressure in the line and the other of said drives providing a horsepower input sufficient to provide a maximum pumping action.

7. An in-line pump adapted to provide two output pressure ranges, which includes a pair of helical screw blade conveyors contained within a common housing, one of said conveyors being adapted to pass its fluid into the other of said conveyors, and separate means to drive said conveyors at two different speeds whereby two pressure ranges may be derived from said pump, said drive means comprising a low speed drive which provides a minimum pumping action and a higher speed drive which provides a maximum pumping action.

8. In an inline pump, a housing in which a plurality of helical blade conveyors are contained, said helical blade conveyors being comprised of a sleeve with a helical blade aiflxed therein, said helical blades in said conveyors being in opposite pitch relation, the first of said conveyors being adapted to pass its fluid into the next adjacent of said conveyors, each of said conveyors having a gear afiixed to the periphery of its sleeve member, a drive means connected to said conveyor gear, and two slip clutches connected to said drive means, each of said slip clutches being in turn connected to a motor whereby said conveyors may be driven by either motor, one of said motors being of relatively low horsepower and adapted to drive said conveyors at a rate which, for any given fluid speed will just prevent backpressure in the fluid line due to passage of said fluid through said pump, the other of said motors being of relatively high horsepower and adapted to positively drive said conveyors at normal pumping output.

9. An in-line fluid pump comprised of two helical blade conveyors contained within a common housing and mounted on a common shaft with their blades in opposite pitch relation, an electric motor of a given horsepower operatively connected with said conveyors and adapted to drive them at one speed for minimum pumping action, a second electric motor of greater horsepower adapted to drive said conveyors at a higher speed, for maximum pumping action and means for connecting and disconnecting said second motor with said conveyor.

10. In an in-line pump, a housing in which a plurality of helical blade conveyors are contained, said helical blade conveyors comprising a sleeve with the helical blades affixed thereto, a common mounting shaft, said helical blades being in opposite pitch relation, said helical blade conveyors being mounted in juxtaposition, each of said conveyors having a gear aflixed to the periphery of its sleeve member, and two gears mating with said gears on said conveyors, each of said mating gears being driven by its respective drive so that one of said drives provides a minimum pumping action while the other of said drives provides a maximum pumping action.

11. In an in-line pump, a housing in which a plurality of helical screw blade conveyors are contained, said helical screw blade conveyors being comprised of a sleeve with the helical screw blades therein afllxed thereto, a common mounting shaft, said helical screw blades. of each adjacent conveyor being in opposite pitch relation, said helical screw blade conveyors being mounted in juxtaposition, each of said conveyors having a gear aifixed to the periphery of its sleeve member, a common drive gear being connected with each gear of the said conveyors to rotate each conveyor in opposite relation to the adjacent conveyor; and clutch means connected to each conveyor gear by said common drive gear, said clutch means being in turn connected to a motor drive means adapted to selectively provide a minimum and maximum pumping action as desired.

12. In an in-line pump, a housing in which a plurality of helical screw'blade conveyors are contained, said helical screw blade conveyors comprising a sleeve with the helical screw blades therein affixed thereto, a common mounting shaft, said helical screw blades of each adjacent conveyor being in opposite pitch relation, said helical screw blade conveyors being mounted in juxtaposition, each of said conveyors having a gear aflixed to the periphery of its sleeve member, a common drive gear being connected with each gear of the said conveyors to rotate each conveyor in opposite relation to the adjacent conveyor, and two slip clutches being connected to each conveyor gear by a common drive gear, said slip clutches being in turn connected to a motor, and the two motors being of different horsepower.

13. An in-line pump which includes: a housing having inlet and outlet ports adapted to be connected into a fluid line; fluid guides secured within said inlet and outlet ports and comprising a tubular hub supported by a plurality of radial vanes extending therefrom; a shaft extending between said guides with its ends mounted in said hubs; a pair of juxtaposed fluid conveyors rotatably mounted on said shaft between said guides, said conveyors each comprising a tubular sleeve opening toward said inlet and said outlet portions of said housing, a central hub in said conveyor having a bore therethrough adapted to receive said shaft and be supported thereon within said housing, and a helical blade between said sleeve and said central hub extending substantially throughout the length thereof, the blades of each of said two conveyors beingof opposite pitch relationship; a ring gear mounted upon the outside of each of said conveyor sleeves and secured thereto to rotate therewith, a driving gear rotatably mounted in said housing and meshing with said ring gears to simultaneously drive said ring gears and their attached conveyors in opposite directions, and separate drives connected to said driving gear, one of said drives providing a minimum pumping action while the other of said drives provides a maximum pumping action.

14. An in-line pump which includes: a housing having inlet'and outlet ports adapted to be connected into a fluid line; fluid guides secured within said inlet and outlet ports and comprising a tubular hub supported by a plurality of radial vanes extending therefrom; a shaft extending between said guides with its ends mounted in said hubs; a pair of fluid conveyors rotatably mounted on said shaft between said guides, said conveyors each comprising a tubular sleeve opening toward said inlet and said outlet portions of said housing, a central hub in said conveyor having a bore therethrough adapted to receive said shaft and be supported thereon within said housing, and a helical blade between said sleeve and said central hub extending substantially throughout the length thereof, the blades of each of said two conveyors being of opposite pitch relationship; a third fluid guide mounted in said housing between said two conveyors comprising a central hub and surrounding said shaft and a plurality of radial vanes extending therefrom, a ring gear mounted upon the outside of each of said conveyor sleeves and secured thereto to rotate therewith, a driving gear rotatably mounted in said housing and meshing with said ring gears to simultaneously drive said ring gears and their attached conveyors in opposite directions, and separate drives connected to said driving gear, one of said drives providing a minimum pumping action while the other of said drives provides a maximum pumping action.

15. An in-line pump which includes a housing having inlet and outlet ports, a shaft mounted within said housing and between said ports, a pair of fluid conveyors rotatably mounted on said shaft, and comprising a tubular sleeve opening toward said inlet and said outlet portions of said housing, a central hub in said conveyor having a bore therethrough adapted to receive said shaft and be supported thereon within said housing, and a helical blad between said sleeve and said central hub extending substantially throughout the length thereof, the blades of each of said two conveyors being of opposite pitch relationship, a ring gear mounted upon the outside of each of said conveyor sleeves and secured thereto to rotate therewith, a driving gear rotatably mounted in said housing and meshing with said ring gears to simultaneously drive said ring gears and their attached conveyors in opposite directions; and separate drives connected to said driving gear, one of said drives providing a minimum pumping action while the other of said drives provides a maximum pumping action.

16. An in-line pump which includes a housing having inlet and outlet ports, a shaft mounted within said housing and between said ports, a pair of fluid conveyors rotatably mounted on said shaft, and comprising a tubular sleeve opening toward said inlet and said outlet portions of said housing, a central hub in said conveyor having a bore therethrough adapted to receive said shaft and be supported thereon within said housing, and a helical blade between said sleeve and said central hub extending substantially throughout the length thereof, the blades of each of said two conveyors being of opposite pitch relationship, a ring gear mounted upon the outside of each of said conveyor sleeves and secured thereto to rotate therewith, a driving gear rotatably mounted in said housing and meshing with said ring gears to simultaneously drive said ring gears and their attached conveyors in opposite directions; apair of driving motors, one of said motors being of greater horsepower than the other, and a slip clutch between each motor and said drive gear whereby the power from either motor may be applied to said conveyors without rotating the unused motor.

17. An in-line pump which includes: a housing having inlet and outlet ports adapted to be connected into a fluid line; fluid guides secured within said inlet and outlet ports and comprising a. tubular hub supported by a plurality of radial vanes extending therefrom; a shaft extending between said guides with its ends mounted in said hubs; a pair of juxtapositioned fluid conveyors rotatably mounted on said shaft between said guides, said conveyors each comprising a tubular sleeve opening toward said inlet and said outlet portions of said housing, a central hub in said conveyor having a bore therethrough adapted to receive said shaft and be supported thereon within said housing, and a helical blade between said sleeve and said central hub extending substantially throughout the length thereof, the blades of each of said two conveyors being of opposite pitch relationship; a ring gear mounted upon the outside of each of said conveyor sleeves and secured thereto to rotate therewith, a pair of driving gears meshed with said ring gears to simultaneously drive said ring gears and their attached conveyors in opposite directions, and separate drives connected to said driving gear, one of said drives providing a minimum pumping action while the other of said drives provides a maximum pumping action.

18. An in-line fluid pump comprising two helical screw blade conveyors contained within a common housing and rotatably mounted therein in juxtaposition with their blades in opposite pitch relation, and gear means to drive said conveyors from either of two drives of different horsepower so that one of said drives provides a minimum pumping action while the other of said drives provides a maximum pumping action.

ROBERT E. SNYDER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 654,654 Lawrence July 31, 1900 791,414 Gordon May 30, 1905 825,652 Holly July 10, 1906 922,756 Degn May 25, 1909 977,107 Loftus Nov. 29, 1910 1,055,308 Beniamins Mar. 11, 1913 1,071,042 Fuller Aug. 26, 1913 1,319,177 Ransom Oct. 21, 1919 1,402,059 Eich Jan. 3, 1922 1,534,451 Kauter i Apr. 21, 1925 1,972,780 Laskowitz Sept. 4, 1934 2,073,404 Hobbs Mar. 9, 1937 FOREIGN PATENTS Number Country Date 18,689 Holland Dec. 15, 1928 51,150 Austria Dec. 11, 1911 210,273 Great Britain Jan. 31, 1924 411,473 France Apr. 12, 1910 

